SCSI Functional Description
2-35
Step 3.
If any wide transfers have been performed using the Chained
Move instruction, read the Wide SCSI Receive bit (
, bit 0) to determine whether a byte is left
in the
register.
2.2.13 SCSI Bus Interface
The LSI53C896 performs SE and LVD transfers, and supports traditional
HVD operation when the chip is connected to external HVD transceivers.
To support LVD SCSI, all SCSI data and control signals have both
negative and positive signal lines. The negative signals perform the SCSI
data and control function. In the SE mode they become virtual ground
drivers. In the HVD mode, the positive signals provide directional control
to the external transceivers. TolerANT technology provides signal filtering
at the inputs of SREQ/ and SACK/ to increase immunity to signal
reflections.
2.2.13.1 LVDlink Technology
To support greater device connectivity and a longer SCSI cable, the
LSI53C896 features LVDlink technology, the LSI Logic implementation of
LVD SCSI. LVDlink transceivers provide the inherent reliability of
differential SCSI, and a long-term migration path of faster SCSI transfer
rates.
LVDlink technology is based on current drive. Its low output current
reduces the power needed to drive the SCSI bus, so that the I/O drivers
can be integrated directly onto the chip. This reduces the cost and
complexity compared to traditional HVD designs. LVDlink lowers the
amplitude of noise reflections and allows higher transmission
frequencies.
The LSI Logic LVDlink transceivers operate in LVD or SE modes. They
allow the chip to detect a HVD signal when the chip is connected to
external HVD transceivers. The LSI53C896 automatically detects which
type of signal is connected, based on the voltage detected by the
DIFFSENS pin. Bits 7 and 6 of the
register
contain the encoded value for the type of signal that is detected (LVD,
SE, or HVD). Please see the
register
description for encoding and other bit information.
*
Summary of Contents for LSI53C896
Page 6: ...vi Preface...
Page 16: ...xvi Contents...
Page 88: ...2 62 Functional Description...
Page 112: ...3 24 Signal Descriptions...
Page 306: ...6 38 Specifications This page intentionally left blank...
Page 310: ...6 42 Specifications This page intentionally left blank...
Page 338: ...6 70 Specifications Figure 6 40 LSI53C896 329 BGA Bottom View...
Page 340: ...6 72 Specifications...
Page 346: ...A 6 Register Summary...
Page 362: ...IX 12 Index...